1. Field of the Invention
The present invention relates generally to a cell culture system that provides extended in vitro culture of neuronal cells. The invention is particularly related to the extended culture of retinal neuronal cells. The cell culture system is useful for identifying bioactive agents that can be used for treating neurodegenerative diseases, particularly retinal diseases and disorders. The invention also relates to using the cell culture method for identifying cells that may be useful for treating a retinal degenerative disease or disorder.
2. Description of the Related Art
In vitro culture of neuronal cells in general, and of retinal neuronal cells in particular, has been problematic. For many years, it has been believed that fully mature neurons lack plasticity and the ability to repair and regenerate after injury. If mature central nervous system (CNS) neurons could be cultured and stimulated to regenerate, transplantation and functional restoration of damaged or diseased CNS tissue might become feasible.
As a first step, groups of investigators have been studying in vitro growth of CNS-derived neurons. Some of these studies involve transformed or immortalized neuronal cells; some cells have been derived from tumorigenic tissues. With respect to retinal cultures, in vitro retinal organ cultures, retinal explant cultures and retinal explant/membrane culture techniques have been reported. In addition, investigators have reported analysis of retinal neural cell cultures that are derived from embryonic tissue or embryonic stem cells or from neonatal retinas. However, the inability to accomplish long-term culture of post-mitotic neuronal cells has been a major roadblock within the field of neurobiology. If primary cells obtained from mature, fully-differentiated neuronal tissue in general, and mature retinal neurons in particular, could be cultured in vitro over an extended period of time, this would constitute a valuable tool for neurobiological studies including examination of cell-to-cell interactions; selection and analysis of neuroactive compounds and materials; provision of a controlled surrogate system for in vivo CNS and ophthalmic tests; and potential analysis single cells from a consistent population.